Truckers have a heck of a lot more key-off power and comfort options than they did 'back in the day'

By Paul Abelson
senior technical editor

Thirty-five years ago, in the days of cheap fuel, no emissions controls and regulated rates, idle reduction was not important to truckers. It was more important to assure your truck started in the morning and that your batteries did not run down.

Very few trucks had generators or auxiliary power units and fewer still had fuel-fired heaters. Those were the only idle-reduction devices available “back in the day.”

As long as there is electricity to turn the engine and fuel that flows, modern diesels will crank at minus 20 degrees and below. Synthetics and new 0W-20 oils assure lubrication at those temperatures.

So, without the excuse of needing to idle to assure that the engine will fire, engine idling is no longer a necessity for some.

However, driver comfort has become a major consideration with engines off. There are numerous idle-reduction technologies available for today’s truckers. Some date back decades, while others are just emerging.

APUs and gen sets
APUs and generators rely on small diesel engines to do what needs to be done without running the big engine. Burning only a fifth of the diesel that the main engine does, both families of equipment provide cab and engine heat, as well as cooling the cab. They also generate electricity for hotel loads such as refrigerators, TVs and other entertainment systems, cooking, lighting and communications.

APUs drive air conditioners and other accessories mechanically. They have their own alternators and air conditioner compressors, and some have pre-oilers, air compressors and other useful devices.

Generators use a small engine to drive a device that converts mechanical energy to electricity. That, in turn, is used to run resistance heaters or heat pumps, air conditioners, battery chargers and other hotel loads.

Depending on engine size – most are two- or three-cylinder – and the number of accessories, prices range from about $3,000 for a simple generator without accessories to more than $11,000 with every accessory possible. They weigh about 400 pounds, give or take 20 to 30 pounds.

While there has been a great deal of growth in popularity of these idle-reduction devices, strict emissions controls may present major problems for their manufacturers.

Led by California, some states are planning regulations on all diesel emissions, including generators and APUs. Engine manufacturers can feed the exhaust from their proprietary units through the diesel particulate filter, or DPF for short, of their own engines as long as they have engineered and certified the installation with EPA.

Third-party suppliers cannot tap into the exhaust system, because it is unlawful to interfere in any way with a certified exhaust system. Smaller manufacturers of generators and APUs may have to purchase DPFs from specialist suppliers.

Truckers with aftermarket units may have to buy aftermarket DPFs, certified by the manufacturers for each make and model of generator or APU. Still under development and not yet required, current guesstimates are that small engine DPFs may run from $2,000 to $3,000.

Fuel the fire
Fuel-fired heaters do not provide summer cooling, but are the most energy- and cost-efficient heating devices. They are experiencing very rapid sales growth, both as stand-alone devices and in combination with cooling equipment. They cost $1,200 and up.

These heaters draw diesel from the vehicle’s tanks, finely atomize it and burn it with a continuous flame in a furnace-like combustion chamber. The chamber is surrounded by air blown through the furnace or by engine coolant pumped by the heater’s integral cooling pump. Because the burn is continuous, emissions are extremely low.

Fuel-fired coolant heaters warm the engine and use OEM heat exchangers and cab fans for occupants’ winter comfort. They burn a tenth of a gallon per hour or less. Air heaters are thermostatically controlled, cycling from high to low heat as needed. Air heaters often use less than a gallon of fuel in two nights.

Battery power
Battery power has improved greatly in just the past decade. Absorbed glass mat designs and gel-type electrolytes provide long life and deep-cycle capabilities. Equipment weights of battery packs are comparable to APUs. Prices vary with air conditioners and numbers of batteries. A system that provides about 10 hours of cooling may cost $3,000 to $6,000.

As battery technology improves through hybrid vehicle development, we’ll see nickel metal hydride batteries that weigh less than lead-acid, with prices getting more competitive.

Deep-cycle battery power allows suppliers to integrate fuel-fired heaters and electric air conditioning. Quite a few truck makers have introduced these electric-diesel hybrid idle-reduction units.

They can also be plugged into shore power, which will extend operating time indefinitely without requiring the main engine to be turned on. Plugging in provides power for hotel loads and keeps batteries topped off. It also can keep engines warm if they have immersion-type, 110-volt plug-in block heaters.

Shore power provides electricity directly to these heaters and appliances that run on household current. When batteries are the sole power source, inverters change the 12-volt direct current to 110-volt or 120-volt alternating current.

The un-common cold
Cold storage is being developed to replace regular air conditioning for engine-off operation. Systems are already available that chill special compounds while the engine and air conditioner are running. With the engine off, electricity from the batteries powers blowers that move air over the compounds to maintain comfortable temperatures in pre-cooled cabs.

Wired for power
Truck stop electrification is among the technologies being encouraged by the Department of Energy and the EPA. A growing number of truck stops have a portion of their spaces equipped with IdleAire. These systems can heat, cool, provide entertainment and Internet services and have plug-ins for electric power.

However, with more and more trucks having onboard idle-reduction systems and more truckers with computers and other entertainment systems, many truck stops, as well as shippers/receivers and trucking company yards, are being electrified with simple shore power – plug-in household current similar to that used by RVs and boats.

Many truck manufacturers now offer integrated HVAC systems and electric hybrid units. From cities to states, governments are getting serious about reducing idling, and the industry is reacting accordingly. In the next few years, there will be an increasing number of optional electric-diesel hybrid idle-reduction systems or manufacturer-integrated, emissions-certified generators and APUs.